The Platform object creates a brick that when touched by a Player will anchor their torso to the brick. This allows for the creation of vehicles that players can stand in and not be flung about the cabin/deck of the vehicle.
The Platform is almost identical to the Seat object, except that instead of sitting down the player will be standing while locked in place. Good for ships.
The Platform object is very useful for making people's characters staying in one spot while they move around, such as a ship or truck. When a player touches the Platform a Weld constraint is created, so they are 'attached' to the Platform and can't move until that weld is broken. It can be removed by hitting the spacebar, when the player jumps to exit the Platform.